Redundant brushless drive systems are used in particular in applications having heightened failure safety, for example in air travel, and are known in principle.
A redundant electric motor is described in EP 0 754 365 B1. In the electric motor described by this reference the rotor includes two magnetic pole pairs disposed axially one-behind-the-other, wherein the stator in particular is formed from two separated coils correspondingly disposed axially one-behind-the-other, each of which is associated with a magnetic pole pair. The two coils are controllable independently of each other. Such an electric motor has the disadvantage that a relatively large installation space is needed for arrangement of the magnetic pole pairs and the coils.
An embodiment of a redundant brushless direct-current motor is described in DE 31 40 034. The direct current motor includes grooved stator windings. The rotor includes four magnetic pole pairs. The stator windings are comprised of four partial strands, and the sensor system is comprised of four sensor groups for the independent position evaluation of the rotor and the commutation of the partial strands. Thus the direct-current motor includes four separately switched and controllable electric motor units. In a parallel operation of the motor units, the total output of the motor is the total of the individual outputs of the motor units. Such a direct-current motor requires a relatively large installation space. Upon the failure of a sensor group or of a partial strand of a motor unit, the other three motor units continue to operate due to the separate partial strands with the associated separate sensor groups. This also has the disadvantage that upon the failure of a motor unit the motor power is relatively lower. Alternatively even only one motor unit can be operated alone, wherein an additional control unit would recognize a failure of the currently active motor unit and then would be switched to another motor unit. This would have the disadvantage that additional components would be needed for such a control unit.
The object of the present invention is to provide a redundant brushless drive system which is formed in a particularly simple, light, and compact manner, wherein the properties of the drive system are formed as equally as possible in the event of recoverable failures.